[Heartbeat] Only retry down monitors on first down check

[andrewvc]

Proposed commit message

When monitors go down we don't want to keep using retries when it was previously down, we only want to retry when it goes down the first time per the retries spec.

Checklist

• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• I have made corresponding change to the default configuration files
• I have added tests that prove my fix is effective or that my feature works
• I have added an entry in CHANGELOG.next.asciidoc or CHANGELOG-developer.next.asciidoc.

Author's Checklist

How to test this PR locally

heartbeat.monitors:
- type: http
  # Set enabled to true (or delete the following line) to enable this monitor
  enabled: true
  # ID used to uniquely identify this monitor in Elasticsearch even if the config changes
  id: my-monitor
  # Human readable display name for this service in Uptime UI and elsewhere
  name: My Monitor
  # List of URLs to query
  urls: ["http://34.42.92.182/pattern?r=200x4,500x6"]
  # Configure task schedule
  schedule: '@every 10s'
  max_attempts: 2

This config should only show a double test on the first 500 (down), then single ones

Related issues

#36147

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• Start Time: 2023-10-02T15:22:59.744+0000

• Duration: 49 min 50 sec

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Test	Results
Failed	0
Passed	2550
Skipped	28
Total	2578

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